1. Field of the Invention
This invention is in the field of bistatic radars, specifically for the synchronization of radar pulses.
2. Description of the Related Art
There are two well known challenges in the design and operation of bistatic radars. The first is to maintain bistatic phase coherency between the transmitter (illuminator) and the receiver. The other challenge is to minimize the direct path signal interference which may saturate and/or corrupt the indirect path signal containing target returns. These two problems severely limit bistatic radar performance for intended applications, such as radar imaging and moving target detection.
Thus, a bistatic radar, because of the separation between the transmit portion (illuminator) and the receiver, is presented with the problem of synchronization of receive and transmit functions. That is, accurate phase information, transmit time, transmitter geo-location needs to be conveyed about the transmitter itself and the transmitted pulse to the receiver to re-constitute a phase coherent image at the receiver. For example, for a bistatic radar there are now two or more separate local oscillators (LO), one in the transmitter (illuminator) and one in each of the receivers that need to be synchronized. In a monostatic radar, the same LO is shared physically by both the transmitter and the receiver, avoiding the need for synchronization between a plurality of remotely located LOs. In general, in the prior art, the transmitter related information may be delivered by a separate data link between transmitter and receiver. Such a data link is prone to failure, would require additional hardware and installation space while having less operational flexibility due to non-universal platform to platform dependency.